+
+    @classmethod
+    def picture_list(cls, filter=None):
+        """Generates a hierarchical listing of all pictures
+        Pictures are optionally filtered with a test function.
+        """
+
+        pics = cls.objects.all().order_by('sort_key')\
+            .only('title', 'slug', 'image_file')
+
+        if filter:
+            pics = pics.filter(filter).distinct()
+
+        pics_by_author = SortedDict()
+        orphans = []
+        for tag in catalogue.models.Tag.objects.filter(category='author'):
+            pics_by_author[tag] = []
+
+        for pic in pics:
+            authors = list(pic.tags.filter(category='author'))
+            if authors:
+                for author in authors:
+                    pics_by_author[author].append(pic)
+            else:
+                orphans.append(pic)
+
+        return pics_by_author, orphans
+
+    @property
+    def info(self):
+        if not hasattr(self, '_info'):
+            info = dcparser.parse(self.xml_file.path, picture.PictureInfo)
+            self._info = info
+        return self._info